JPH11345606A - Battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery and a manufacturing method thereof which are advantageous to improvement in assembly characteristics. SOLUTION: A porous resin layer 14 is laminated integrally on at least one surface of an electrode (for example, a positive electrode 1) and the resin layer 14 is a separator. A manufacturing method comprises the following steps. Liquid material containing resin is sprayed on at least one surface of the electrode (for example, the positive electrode 1) and the porous resin layer 14 is laminated integrally on the electrode. After that, the electrode is assembled to form a battery and the resin layer 14 laminated integrally on the electrode is used as a separator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery provided with electrodes and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a battery has two kinds of electrodes constituting a positive electrode and a negative electrode, a separator interposed between the negative electrode and the positive electrode to prevent a short circuit therebetween, and a battery between the negative electrode and the positive electrode. And an intervening electrolyte. The separator is
This is for preventing contact between the positive electrode and the negative electrode.

In such a battery, the surface of a sheet-shaped negative electrode containing a hydrogen storage alloy as a negative electrode active material is coated with a polymer to reduce the frictional resistance of the negative electrode, thereby winding the negative electrode spirally. It is easy to rotate, and furthermore, a positive electrode, a negative electrode, and a cloth separator, which is a separate body, are arranged between the positive electrode and the negative electrode. (Japanese Patent Laid-Open No. 5-1
No. 82687).

As a porous separator separate from the positive electrode and the negative electrode, there is known a porous separator in which spherical resin particles are adhered to each other and a gap for holding an electrolytic solution is formed between adjacent spherical resin particles. (Japanese Patent Laid-Open No. 1-1679)
No. 48).

[0005]

In the above-mentioned battery, since the separator is in the form of a sheet separate from the electrodes, there is room for improvement in assemblability. The present invention has been made in view of the above circumstances, and has as its object to provide a battery that is advantageous for improving the assemblability and a method for manufacturing the same.

[0006]

A battery according to the present invention is a battery provided with electrodes, in which a porous resin layer is integrally laminated on at least one surface of the electrode, and the resin layer is used as a separator. It is characterized by the following. The method for manufacturing a battery according to the present invention includes spraying a liquid material containing a resin on at least one surface of the electrode to integrally laminate a porous resin layer on the electrode, and then assembling the electrode to form a battery. The present invention is characterized in that a resin layer integrally laminated on an electrode is used as a separator.

[0007]

According to the battery of the present invention, a porous resin layer is integrally laminated on at least one surface of an electrode, and the resin layer is used as a separator. The resin layer according to the present invention may be laminated on both sides of the electrode, or may be laminated on one side. The electrode on which the resin layer functioning as a separator is stacked may be a positive electrode or a negative electrode.

If the thickness of the resin layer functioning as a separator is too small, a short circuit may occur between the positive electrode and the negative electrode. If the thickness of the resin layer is too large, the distance between the positive electrode and the negative electrode becomes longer, the movement distance of active material ions increases, and the internal resistance of the battery may increase. Considering these points, the thickness of the resin layer functioning as a separator is
It can be about 25 to 60 μm and about 25 to 40 μm. However, it is not limited to this.

[0009] The resin layer is porous. The porosity of the resin layer is preferably about 30 to 60% by volume, and more preferably 40 to 50%, in consideration of the retention of the electrolyte. However, it is not limited to this. As a resin constituting the resin layer, for example, a thermoplastic resin containing an olefin-based resin such as polyethylene (PE) or polypropylene (PP) can be adopted.

According to the manufacturing method of the present invention, a step of integrally laminating a porous resin layer on the electrode is performed by spraying a liquid material containing a resin on at least one surface of the electrode. In this case, as described above, it may be sprayed on only one side of the electrode, or may be sprayed on both sides of the electrode. The electrode may be a positive electrode or a negative electrode. As a method of laminating the resin layer on the electrode, a method of spraying and applying a liquid material containing resin as a main component can be adopted. In this case, spraying can be performed using gas. Air can be used as the gas, but nitrogen gas or a rare gas may be used.
The temperature of the gas may be room temperature or may be heated. When the gas is heated, the spray drier property is improved, and it is advantageous to dry the liquid material containing a resin as a main component at the early stage of spray coating. If a solvent that evaporates is added to the liquid, the porosity of the resin layer can be easily adjusted.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the positive electrode 1 is formed by laminating active material layers (thickness: 55 μm) 11 and 12 on a foil-shaped aluminum-based current collector 10 (thickness: 15 μm). And a resin layer 14 laminated thereon. Active material layer 11, 1
2 was formed as follows. That is, lithium oxide powder (LiCoO _{2 having} an average particle size of 1) functioning as a positive electrode active material.
0-20 μm), a paste-like mixture obtained by mixing carbon powder (average particle diameter 1-2 μm) that functions as a conductive material, and polyvinylidene fluoride (PVDF) that functions as a binder. The mixture is applied to both surfaces of the current collector 10 by a drying method, and then dried by a dryer for scattering a solvent (18).
(0 ° C. × 2 hours), the active material layers 11 and 12 are laminated on the current collector 10, and then the resin layer 14 is coated on the active material layer 11, whereby the positive electrode 1 (width 54 mm) is formed. It is configured.

As shown in FIG. 3, the negative electrode 2 is formed by laminating an active material layer 21 (thickness: 35 μm) on a copper-based current collector 20 (thickness: 10 μm) in a foil shape. In this case, a paste-like mixture of carbon powder (natural graphite, average particle size of 10 to 20 μm) functioning as a negative electrode active material and polyvinylidene fluoride (PVDF) functioning as a binder is used. The mixture is collected by the machine
0, and then dried (vacuum drying, 180 ° C x
2 hours), the active material layer 21 is laminated on the current collector 20, thereby forming the negative electrode 2 (55 mm in width).

According to this embodiment, the resin layer 14 of the positive electrode 1 was formed as follows. That is, as shown in FIG. 4, a roll-shaped positive electrode sheet 3 including a current collector 10 and active material layers 11 and 12 is used, and sprayed at a distance LA (for example, 120 mm) above the positive electrode sheet 3. The device 4 is arranged. The spray device 4 is a nozzle 4 capable of spraying and spraying a resin (polypropylene) melted by heating.
0, an air supply pipe 42 which is connected to an air source 41 and supplies air for spraying, and a liquid 4 containing a resin as a main component (an evaporating solvent may be added).
And a resin supply source 44 that feeds the resin to zero.

In the above-described state, with the flat surface of the positive electrode sheet 3 protruding, the spray device 4 is driven while moving the positive electrode sheet 3 at a predetermined speed in the longitudinal direction, that is, in the direction of arrow X1.
Is applied by spraying from a nozzle 40. As a result, the resin layer 14 is integrally joined and laminated on one surface, which is the upper surface of the positive electrode sheet 3, thereby forming the positive electrode 1. In this embodiment, the thickness of the resin layer 14 is 30 μm ± 3 μm.
m, and the porosity was about 30 to 60% by volume. The porosity was determined from the weight change when the electrolyte was impregnated.

The above-mentioned spraying conditions include a positive electrode
The traveling speed of G3 is 2 cm / sec, and the nozzle diameter is 1.3.
mm, spray distance 120mm, air pressure 3.0kgf /
cm ^TwoAnd When the width of the positive electrode sheet 3 is large,
Is at least one of the spray device 4 and the positive electrode sheet 3
Along the transverse direction of the positive electrode sheet 3, that is, the arrow Y direction.
Can be moved.

FIG. 2 is a conceptual diagram showing the inside of the resin layer 14.
According to the present embodiment, when the resin layer 14 is laminated, the particles having the liquid resin component sprayed from the nozzle 40 of the spray device 4 collide with the positive electrode sheet 3 and are flattened. It is thought that. Therefore, as shown in FIG. 2 as a conceptual diagram, it is considered that the internal structure of the resin layer 14 exhibits a scale-like laminated structure having a large number of pores 14c or a structure similar thereto.

After laminating the resin layer 14 as described above,
As shown in FIG. 5A, an intermediate roller 60 holding the positive electrode 1 on which the resin layer 14 is laminated, an intermediate roller 62 holding the negative electrode 2, and a winding for laminating the positive electrode 1 and the negative electrode 2 Using the roller 64, the winding roller 64 is driven to rotate in the direction of arrow Z while applying tension T in the longitudinal direction of the positive electrode 1 and the negative electrode 2, thereby winding the winding roller in a state where the positive electrode 1 and the negative electrode 2 are stacked. Wrap around 64. A resin layer 14 functioning as a separator is interposed between the positive electrode 1 and the negative electrode 2. The length of the positive electrode 1 is 600 mm, and the length of the negative electrode 2 is 6 mm.
It was 25 mm.

The positive electrode 1 and the negative electrode 2 are assembled inside the battery can, and an electrolytic solution (solvent: EC (ethylene carbonate): DEC (diethyl carbonate) = 2) is attached to the battery can.
0:80, electrolyte: LiClO _4, concentration: 1.0 mol / l), sealed and battery (18650 siz)
e, Φ18 mm × 65 mm). FIG. 5
(B) schematically shows a winding step when the positive electrode and the separator are separate bodies. As shown in FIG. 5B, the intermediate roller 60 for the positive electrode 1 'and the intermediate roller 6 for the negative electrode 2'
In addition to 2, intermediate rollers 65 and 66 for the separator M are required, and a four-axis system is used. In order to uniformly wind the positive electrode 1 ′, the negative electrode 2 ′, and the separator M while stacking them, the rotation control of the winding roller 64 is performed. In addition, each of the intermediate rollers 60, 62, 6
5, 66 rotation control is also required, and the control at the time of electrode winding becomes complicated. In this regard, in this embodiment, since the resin layer 14 functioning as a separator is integrally laminated with the positive electrode 1, as can be understood from FIG. 5A, in addition to the rotation control of the winding roller 64, Each intermediate roller 60,
What is necessary is just to perform the rotation control of 62, and the advantage that control at the time of electrode winding becomes easy is obtained.

According to the present embodiment, since the resin layer 14 functioning as a separator is integrally laminated with the positive electrode 1, if the positive electrode 1 and the negative electrode 2 are directly assembled as a battery, unlike the conventional case, The step of assembling the separator becomes unnecessary. Furthermore, since the resin layer 14 functioning as a separator covers the active material layer 11 of the positive electrode 1 integrally, it is advantageous to prevent the active material layer 11 from falling off in an assembling step or the like. Therefore, it is advantageous to exhibit the target performance of the battery.

When the separator is formed by using a fiber-based cloth, anisotropy due to the fiber direction is likely to occur, and the degree of freedom of the separator in bending shape is restricted. In this regard, according to this embodiment, as described above, the particles having the liquid component collide with the positive electrode sheet 3 and are flattened, and the flattened particles are deposited to form the resin layer 14. Therefore, the degree of anisotropy of the resin layer 14 is reduced. Therefore, when bending the positive electrode 1, the resin layer 14 functioning as a separator has a large degree of freedom in bending shape. Therefore, it is suitable for a battery of a spirally wound type.

The particles having the liquid component collide with the positive electrode sheet 3 and flatten, and the flattened particles are deposited and the resin layer 14 is formed, so that the pores 14 c formed in the resin layer 14 are formed. Is unlikely to stand upright with respect to the positive electrode 1, tends to be flat, and tends to be randomly arranged. Therefore, even if lithium dendrite is generated in the positive electrode 1, it is advantageous to suppress the lithium dendrite from penetrating the pores 14c of the resin layer 14. Therefore, it is advantageous for suppressing a short circuit between the electrodes caused by the lithium dendrite.

(Test Example) The performance of the battery according to the above-described example product was tested. The battery according to the comparative example was similarly tested. The battery of the comparative example has the same size and the same structure as the battery of the example, but the positive electrode and the separator are separate bodies. In this case, the charge / discharge load characteristics were examined at 1 to 6 mA / cm ² after charge / discharge at 1/5 C for 2 cycles. FIG. 6 shows the result.

In FIG. 6, the mark ○ indicates the time of charging the product of the example, the mark Δ indicates the time of discharging of the product of the embodiment, the mark ● indicates the time of charging of the product of the comparative example, and the mark × indicates the time of discharging of the product of the comparative example. As can be understood from the test results in FIG. 6, the load characteristics of the example product were equal to or slightly better than those of the comparative example. In particular, as can be seen from FIG. 6, as the current density increases from 5 to 6 mA / cm ² , the battery of the example product becomes better than the battery of the comparative example.

The cycle characteristics of the battery according to the example and the battery according to the comparative example were also examined at 1 mA / cm ² . FIG. 7 shows the result. In FIG. 7, the mark ○ indicates the product of the example, and the mark ● indicates the product of the comparative example. As can be understood from the test results of FIG. 7, the example product had cycle characteristics comparable to the comparative example product. Based on the above results, the battery of the example product can improve the assemblability while securing the battery performance with respect to the battery of the comparative example product.

(Application Example) FIG. 8 shows a main part of an application example applied to a cylindrical battery. In this example, a positive electrode 1 and a negative electrode 2 are spirally wound and housed in a housing chamber 71 of a cylindrical battery can 70 constituting a battery. Battery can 70
A battery cover 74 is attached via a gasket 75. The storage chamber 71 stores an electrolytic solution. Further, it is needless to say that the present invention is not limited to the cylindrical battery, but may be applied to a button battery, a coin battery, and a square battery.

The battery shown in FIG. 8 is an example applied to a battery in which a positive electrode and a negative electrode are spirally wound. However, the present invention is not limited to this. Of course, it may be applied to a battery.

[0027]

According to the battery of the present invention, a porous resin layer is integrally laminated on at least one surface of the electrode, and the resin layer is used as a separator. For this reason, compared to a method in which a separate separator and electrode are assembled,
The battery assembly process can be facilitated. Further, if the resin layer covers the active material layer of the electrode, it is advantageous to prevent the active material layer from falling off.

According to the manufacturing method of the present invention, a porous resin layer is integrally laminated on the electrode by spraying a liquid material containing a resin on at least one surface of the electrode.
A battery is formed by assembling the electrodes, and a resin layer integrally laminated on the electrodes is used as a separator. Therefore, the battery assembling process can be facilitated as compared with a method in which a separate separator and an electrode are assembled. Further, if the resin layer covers the active material layer of the electrode, it is advantageous to prevent the active material layer from falling off.

[Brief description of the drawings]

FIG. 1 is a sectional view of a positive electrode.

FIG. 2 is a conceptual diagram schematically showing an internal structure of a resin layer of a positive electrode.

FIG. 3 is a sectional view of a negative electrode.

FIG. 4 is a process diagram schematically showing a mode in which a resin layer is sprayed on a positive electrode sheet.

FIG. 5A is a process diagram schematically showing a mode of winding a positive electrode and a negative electrode according to an example, and FIG. 5B is a process diagram schematically showing a mode of winding a positive electrode and a negative electrode according to a conventional example. is there.

FIG. 6 is a graph showing charge / discharge load characteristics.

FIG. 7 is a graph showing cycle characteristics.

FIG. 8 is a perspective view of a main part of a battery according to an application example.

[Explanation of symbols]

In the figure, 1 is a positive electrode, 10 is a current collector, 11 is an active material layer, 14
Denotes a resin layer, 4 denotes a spray device, and 40 denotes a nozzle.

Claims (2)

[Claims] 1. A battery provided with an electrode, wherein a porous resin layer is integrally laminated on at least one surface of the electrode, and the resin layer is used as a separator. 2. A porous resin layer is integrally laminated on the electrode by spraying a liquid material containing a resin on at least one surface of the electrode. Thereafter, the electrode is assembled to form a battery, and the electrode is integrated with the electrode. A method for producing a battery, comprising using a resin layer that is laminated in a stacked manner as a separator.